package com.cu.jiekong.util;

import java.security.MessageDigest;
import java.util.Random;
import java.util.UUID;

/**
 * 字符串工具类
 * @author jintian
 * @date 15:14
 */
public class StringUtil {
    /**
     * 对字符串进行MD5
     *
     * @param paramStr
     * @return
     */
    public static String MD5(String paramStr) {
        if (paramStr == null) {
            paramStr = "";
        }


        char hexDigits[] = {
                '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F'
        };
        try {
            byte[] btInput = paramStr.getBytes();
            // 获得MD5摘要算法的 MessageDigest 对象
            MessageDigest mdInst = MessageDigest.getInstance("MD5");
            // 使用指定的字节更新摘要
            mdInst.update(btInput);
            // 获得密文
            byte[] md = mdInst.digest();
            // 把密文转换成十六进制的字符串形式
            int j = md.length;
            char str[] = new char[j * 2];
            int k = 0;
            for (int i = 0; i < j; i++) {
                byte byte0 = md[i];
                str[k++] = hexDigits[byte0 >>> 4 & 0xf];
                str[k++] = hexDigits[byte0 & 0xf];
            }
            return new String(str);
        } catch (Exception e) {
            return null;
        }
    }


    public static String UUIDStr() {
        UUID uuid = UUID.randomUUID();
        return uuid.toString().replace("-", "");
    }

    public static long UUID(int n) {
        if (20 < n || n <= 0) {
            throw new RuntimeException("输入长度有误");
        }

        Random random = new Random();
        long result = 0;
        for (int i = 0; i < n; i++) {
            result = result * 10 + random.nextInt(10);
        }
        return result;
    }

    public static long UUID() {
        return UUID(12);
    }

}
